Efficient Water Oxidation Using Ta<sub>3</sub>N<sub>5</sub> Thin Film Photoelectrodes Prepared on Insulating Transparent Substrates
Tomohiro Higashi, Hiroshi Nishiyama, Yuki Otsuka, Yudai Kawase, Yutaka Sasaki, Mamiko Nakabayashi, Masao Katayama, Tsutomu Minegishi, Naoya Shibata, Kazuhiro Takanabe, Taro Yamada, Kazunari Domen
Abstract
Abstract Photoelectrochemical (PEC) water splitting using visible‐light‐responsive photoelectrodes is the preferred approach to converting solar energy into hydrogen as a renewable energy source. A transparent Ta 3 N 5 photoanode embedded within a PEC cell having a tandem configuration is a promising configuration that may provide a high solar‐to‐hydrogen energy conversion efficiency. Ta 3 N 5 thin films are typically prepared by heating precursor films in an NH 3 flow at high temperatures, which tends to degrade the transparent conductive layer, such that producing efficient Ta 3 N 5 transparent photoanodes is challenging. Herein, the direct preparation of transparent Ta 3 N 5 photoanodes on insulating quartz substrates was demonstrated without the insertion of a transparent conductive layer. The resulting devices generated a photocurrent of 6.0 mA cm −2 at 1.23 V vs. a reversible hydrogen electrode under simulated sunlight. This study provides a new strategy for the preparation of transparent photoelectrodes that mitigates current challenges.